The present invention relates to an improved thermal window design for both fixed and operating type windows and more specifically is drawn to an improved design which allows for the unit stacking of fixed and operating type windows within the same frame member.
In recent years it has become highly desirable to use light metallic structural materials such as aluminum for the frame members in both fixed and operating type windows. The major disadvantage of using highly thermal conductive materials for the frame and vent members of thermal windows is that heat is transferred between the interior and exterior parts of the window which results in the formation of condensation on the warm side of the window as well as heat loss therefrom.
In order to eliminate the heat lost between the interior and exterior portions of a metal window frame in fixed type windows it has become commonplace in the art to form a thermal break between the exterior and interior frame portions. A typical thermal break is taught in U.S. Pat. No. 2,877,515 wherein a thermal break is accomplished by providing separate framing members for the exterior and interior and connecting the members by introducing a barrier of non-metallic insulating material therebetween. While the arrangement disclosed in the aforenoted U.S. patent provides a sufficient thermal barrier in fixed type windows, there are substantial disadvantages associated with such a design. The need for providing an insulating member between the frame member greatly increases the cost of manufacturing the window. In addition, the window frame is inherently weakened. Furthermore, the integrity of the longevity of the insulating material as a connecting member is questionable. Naturally, it would be highly desirable to provide a thermally broken window without the need of an insulating member as previously discussed.
U.S. Pat. No. 3,308,582 to Bakke and German Offenlegungsschrift No. 2,300,358 both disclose operating type thermal windows in which a thermal barrier is established between the frame and vent members. However, in both the Bakke and the German patent the frame and vent members are in indirect contact via a thermal insulating member. In addition to the above, the window disclosed in the Bakke patent requires that the vent be disassembled in order to install the glass.
Aside from the aforenoted disadvantages exhibited by the prior art with regard to insulating, a further and still more important disadvantage of thermal window designs heretofore known is the inability to provide a single window frame which is capable of accepting both fixed glass face members and operating vent members thereby allowing for easy unit stacking of fixed and operating windows. Heretofore, in order to stack fixed and operating thermal windows it was necessary to provide separate frame members of different size and configuration for both the fixed and operating type windows which results in a number of inherent disadvantages. In order to achieve uniform sight lines, which is highly desirable from an architectural standpoint, additional framing members were required resulting in an increase in cost and an increase in the size of the sight lines.
Accordingly, it is a principal object of the present invention to provide an improved thermal window of both the fixed and operating type which is designed to be thermally broken without the need of an insulating material as a thermal break.
It is a particular object of the present invention to provide an improved thermal window design in which both fixed and operating type windows are easily unit stacked on the same frame member.
It is a further object of the present invention to provide an improved operating type thermal window which is easily assembled.
It is still a further object of the present invention to provide an efficient thermal window which is inexpensive to manufacture.
It is a further particular object of the present invention to provide an improved thermal window design which is architecturally pleasing.
Further objects and advantages of the present invention will be evident from what appears hereinbelow.